Negative charging selenium photoreceptor

Abstract

An x-ray photoreceptor for use in a xerographic system having a high arsenic layer 5 to 40 microns in thickness between the substrate and the selenium layer for trapping positive charge injected from the interface. Since this positive charge otherwise tends to discharge a negatively charged plate, the provision of this trapping layer will allow the plate to be used for either positive or negative charging.

We claim: 
     
       1. An x-ray selenium protoreceptor comprising: a conductive substrate having a surface,   a semiconductor selenium bulk layer 150 to 450 microns in thickness having an arsenic concentration of 0.01 to 1% by weight and a chlorine concentration of 3 to 20 parts per million, and having a surface adjacent to said substrate and an other surface,   a first layer of selenium arsenic alloy 0.1 to 33% arsenic by weight and 0.05 to 5 microns in thickness in contact with said substrate surface for retarding the formation of artifact producing selenium crystallites between said substrate surface and said first layer, and   a second layer of selenium arsenic alloy 0.1 to 33% arsenic by weight 5 to 40 microns in thickness between, and in contact with, said first and bulk layers for trapping positive charges when the bulk layer is negatively charged with respect to the substrate.   
     
     
       2. The photoreceptor of claim 1 wherein said substrate is transparent. 
     
     
       3. The photoreceptor of claim 1 wherein said substrate is opaque. 
     
     
       4. The photoreceptor of claim 1 further comprising a third layer of arsenic rich selenium 0.1 to 33% arsenic by weight doped with 3 to 20 parts per million chlorine 5 to 40 microns in thickness on the other surface of said bulk layer to trap positive charges when the bulk layer is positively charged with respect to the substrate, and to retard the formation of artifact-producing selenium crystallites at the other bulk layer surface.